The present invention relates to a platen of the flat type for an impact printer.
In impact printers, such as serial dot matrix printers, the print is obtained by means of impression elements (in this case needles) arranged on a print head; the needle act on an inked ribbon and are pushed hard against a sheet of paper that is supported on a printing platen.
In one particular category of impact printers, the platen is of the flat type. In this case the platen generally consists of a metal section, giving a high accuracy of manufacture; this ensures that the head is maintained at a correct distance from a free surface of the sheet of paper upon which the needles act. A strip of plastics material is glued to a surface of the metal section on which the sheet of paper is supported; this plastics strip acts as a support for the sheet of paper, so as not to damage the needles and the inked ribbon. Two strips of anti-noise material (made for example of a lead-based material) are glued to corresponding lateral surfaces of the metal section, to reduce the vibrations and the noise produced during printing. Moreover, in the case when the platen is not fixed rigidly to a frame of the printer, two blocks of plastics material are 25 provided, screwed to the longitudinal ends of the metal section, each of which is connected to a corresponding elastic support; these connecting blocks reduce the vibrations transmitted from the platen to the frame of the printer.
A drawback with known platens is that the operations of gluing of the plastics strip and of the anti-noise strips to the metal section (and the operations of screw-fixing of the connecting blocks if required) introduce inaccuracies in assembly; therefore it is necessary to provide a subsequent stage of correction of the platen.
This correction stage, combined with the operations of gluing of the plastics strip and of the anti-noise strips (and with the possible operations of screw-fixing of the connecting blocks) make the platen extremely expensive, which affects the final cost of the whole printer.
Furthermore, management of the various components of the platen (metal section, plastics strip, anti-noise strips and connecting blocks if present) introduces significant logistical difficulties in management of the various suppliers.
The object of the present invention is to overcome the abovementioned drawbacks. To achieve this object, a platen of the flat type for an impact printer as described in the first claim is proposed.
Briefly, there is provided a platen of the flat type for an impact printer comprising a metal body for support and a plastics body for protection and absorption of vibrations wherein the metal body is embedded in the plastics body.
Furthermore, the present invention also proposes an impact printer comprising the said platen and a corresponding method of manufacture of the platen.